1. Field of the Invention
This invention relates to a liquid discharging head for discharging desired liquid by the creation of air bubbles created by heat energy being caused to act on liquid, a head cartridge using the liquid discharging head, a liquid discharging device and a liquid discharging method. It further relates to an ink jet kit having such liquid discharging head.
The present invention particularly relates to a liquid discharging head having a movable member displaceable by the utilization of the creation of air bubbles, a head cartridge using the liquid discharging head, and a liquid discharging device.
More particularly, the present invention relates to a liquid discharging head which, in a construction using the above-described movable member, enables the stable supply of high-viscosity ink, can improve the refill of liquid creating air bubbles, can present liquid mixing during the non-driving of upper and lower liquids vertically spaced apart from each other by the movable member and can present discharged liquid from flowing into a heat generating member being driven beyond the movable member, a head cartridge using this liquid discharging head, a liquid discharging device, a liquid discharging method and a recording method.
Also, the present invention is an invention which can be applied to apparatuses such as a printer for effecting recording on a recording medium such as paper, yarn, fiber, cloth, hides, metals, plastics, glass, wood or ceramics, a copying apparatus, a facsimile apparatus having a communication system, and a word processor having a printer unit, and further an industrial recording apparatus compositely combined with various processing apparatuses.
The "recording" in the present invention means not only imparting images having meanings such as characters and figures to a recording medium, but also imparting images having no meaning such as patterns.
2. Related Background Art
There is known an ink jet recording method, i.e., a so-called bubble jet recording method, in which energy such as heat is given to ink to thereby cause a state change accompanied by a sharp volume change (creation of air bubbles) to the ink and the ink is discharged from a discharge port by an acting force based on this state change and is caused to adhere to a recording medium to thereby effect image formation. In a recording apparatus using this bubble jet recording method, as disclosed in U.S. Pat. No. 4,723,129, etc., there are generally disposed a discharge port for discharging ink, an ink flow path communicating with this discharge port, and an electro-thermal converting member as energy generating means disposed in the ink flow path for discharging the ink.
According to such a recording method, images of high dignity can be recorded at high speed and with low noise and in a head for effecting this recording method, discharge ports for discharging the ink can be disposed at high density and therefore, there are many excellent points such as recorded images of high resolution and further color images being capable of being easily obtained by a compact apparatus. Therefore, this bubble jet recording method has been utilized in many office apparatuses such as printers, copying apparatuses and facsimile apparatuses, and further in industrial systems such as textile printing apparatuses in recent years.
As the bubble jet technique is utilized for products in many fields, the following requirements have heightened in recent years.
For example, as a study for the requirement for improved energy efficiency, mention is made of the optimization of a heat generating member such as adjusting the thickness of protective film. This technique is effective in improving the efficiency of the propagation of generated heat to liquid.
Also, in order to obtain images of high quality, there has been proposed a driving condition for providing a liquid discharging method or the like in which the discharge speed of ink is high and which can effect good ink discharge based on the stable creation of an air bubble, and there has been proposed a method in which from the viewpoints of high-speed recording, the shape of a liquid flow path is improved to provide a liquid discharging head which is high in the refill speed of discharged liquid into the liquid flow path.
Of this shape of the flow path, one as shown in FIGS. 1A and 1B of the accompanying drawings is described as flow path structure in Japanese Laid-Open Patent Application No. 63-199972, etc. The flow path structure and head manufacturing method described in this publication are inventions which pay attention to a back wave created with the creation of an air bubble (pressure travelling in a direction opposite to the direction toward a discharge port, i.e., pressure travelling toward a liquid chamber 12). This back wave is not energy travelling in the discharging direction and is therefore known as loss energy.
The invention shown in FIGS. 1A and 1B discloses a value 10 spaced apart from an air bubble creation area formed by a heat generating element 2 and located on a side opposite to discharge ports 11 with respect to the heat generating element 2.
In FIG. 1B, this value 10 is disclosed as one having an initial position like being stuck on the ceiling of a flow path 3 by a manufacturing method utilizing a plate material or the like, and hanging down into the flow path 3 with the creation of an air bubble. This invention is disclosed as one which controls a part of the above-described back wave by the value 10 to thereby suppress energy loss.
In this construction, however, it will be seen that it is not practical to liquid discharge to suppress a part of the back wave by the value 10 as will be seen if study is made of the time when an air bubble has been created in the flow path 3 holding the liquid to be discharged.
Originally, the back wave itself has no direct relation to discharge as previously described. At a point of time where this back wave has been created in the flow path 3, the pressure of the air bubble which is directly related to discharge has already made the liquid dischargeable from the flow path 3, as shown in FIG. 1B. Accordingly, it is apparent that even if a part of the back wave is suppressed, it will not greatly affect discharge.
On the other hand, in the bubble jet recording method, a heat generating member repeats heating while being in contact with ink and therefore, a deposit by the scorching of the ink is created on the surface of the heat generating member, and depending on the kind of the ink, a great deal of such deposit is created whereby the creation of air bubbles is made unstable and in some cases, it has been difficult for the good discharge of the ink to take place. Also, when the liquid to be discharged is liquid liable to be deteriorated by heat or is liquid difficult to provide bubbling sufficiently, there has been desired a method for discharging the liquid wall without changing the quality of the liquid to be discharged.
From such a point of view a method in which liquid for creating an air bubble by heat (bubbling liquid) and liquid to be discharged (discharge liquid) are made discrete from each other and the pressure by bubbling is transmitted to the discharge liquid to thereby discharge the discharge liquid is disclosed in Japanese Laid-Open Patent Application No. 61-69467, Japanese Laid-Open Patent Application No. 55-81172, U.S. Pat. No. 4,480,259, etc. In these publications, there is adopted a construction in which ink which is the discharge liquid and the bubbling liquid are completely separated from each other by flexible film such as silicone rubber so that the discharge liquid may not directly contact with a heat generating member and the pressure by the bubbling of the bubbling liquid is transmitted to the discharge liquid by the deformation of the flexible film. By such a construction, the prevention of a deposit on the surface of the heat generating member and an improvement in the degree of freedom of choice of the discharge liquid are achieved.
However, a head of the construction as previously described in which the discharge liquid and the bubbling liquid are completely separated from each other is of a construction in which the pressure during bubbling is transmitted to the discharge liquid by the expansion and contraction of the flexible film and therefore, the flexible film considerably absorbs the pressure by bubbling. Also, it is possible to obtain the effect by separating the discharge liquid and the bubbling liquid from each other because the amount of deformation of the flexible film is not very great, but there has been the possibility of energy efficiency and discharging force being reduced.